Short answer: It depends. Your thyroid gland governs much of the metabolic activity in your body, and when it’s underactive (meaning it’s not producing enough thyroid hormone), that can cause all sorts of symptoms, including weight gain, feeling cold, and fatigue. However, sometimes hypothyroidism is so minor that there are only very mild, nonspecific symptoms, or none at all, and it’s detectable only through blood tests.

To treat hypothyroidism, a patient needs to take a hormone medication to replace the amount that the thyroid can’t make. Borderline cases can progress to overt hypothyroidism, so some say it’s useful to take medication, especially if you also have a risk of heart disease; even mild hypothyroidism can lead to elevated cholesterol levels.

That said, other research suggests that taking medication for subclinical hypothyroidism (another name for borderline underactive thyroid) may have no benefit. If you’re not experiencing any symptoms, you should think about whether the potential side effects (such as loss of bone density) are worth it.

Your primary care physician or an endocrinologist can help you weigh the costs and benefits of treatment in your case. Your MD may have you hold off on taking medication and get regular tests to monitor your levels. Or, if you have symptoms, she may advise taking the medication temporarily to see whether you start to feel better.

Health’s medical editor, Roshini Rajapaksa, MD, is assistant professor of medicine at the NYU School of Medicine.